This invention relates generally to insulated covers or lids for mounting over a tank containing a heated fluid such as water, particularly such as a therapeutic spa tub or hot tub or the like. More specifically, this invention relates to a relatively simple, lightweight, and inexpensive insulated cover of the type shown and described in U.S. Pat. No. 5,619,759, designed for minimizing water heat and evaporative losses while additionally safeguarding against foreign objects and/or persons falling into the fluid-containing tank, but wherein the improved insulated cover is conveniently foldable to a reduce size configuration for facilitated shipping and storage.
Thermal covers for use with swimming pools and spa tubs and the like are generally known in the art. In one common form, such thermal covers comprise a flexible blanket of vinyl or other suitable plastic material to float on the water surface. The flexible blanket is designed to provide an insulative structure which is substantially impermeable to passage of water and air, whereby heat is substantially retained within the body of water and evaporative losses are substantially minimized. Alternative thermal covers which function in an analogous manner include an array of floating objects such as hollow plastic balls which substantially cover the water surface to retain heat and minimize evaporation. However, pool and spa covers of these types provide minimal protection against foreign objects falling into the pool or spa, particularly with respect to safeguarding against a child or other person falling into the water.
Other protective covers for swimming pools and spa tubs and the like have included relatively high strength blankets of canvas-backed or reinforced plastic or vinyl materials, in combination with anchor devices for retaining the blanket in a configuration stretched over the water surface. Such covers beneficially provide protection against persons and foreign objects falling into the water, but proper attachment of the cover to the requisite anchoring devices represents a time consuming and often difficult task. Moreover, the anchoring devices typically require permanent attachment to structural walls or decking surfaces surrounding the pool or spa tub.
U.S. Pat. No. 5,619,759 discloses an improved insulated cover for use with a spa tub or hot tub or the like, wherein a relatively lightweight panel of insulated foam or the like is used in combination with a structural membrane of relatively high tensile strength fabric stretched over an outer or peripheral frame ring. The structural membrane, typically in cooperation with a decorative top cover sheet, retains the insulation material in a position extending over the spa or hot tub to retain heat and prevent excess evaporation. In addition, the structural membrane provides a lightweight yet effective physical structure for withstanding substantial vertical loads, whereby the cover safeguards against persons or other objects falling into the water. Despite these benefits and advantages, however, the insulated cover described in U.S. Pat. No. 5,619,759 is not designed for convenient folding to a compact size and shape conducive to convenient shipping and/or storage.
The present invention represents a further improvement in and to insulative covers for a fluid-containing tank such as a spa tub or hot tub, particularly of the type shown and described in U.S. Pat. No. 5,619,759, wherein the cover is adapted to be folded to a convenient and compact profile for shipping and/or storage, yet wherein the cover when erected includes a high tensile strength structural membrane capable of accommodating substantial vertical loads.